Letters
Plano, Texas (Dao, Stager); Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas (Birch). Corresponding Author: Simone L. Li, PhD, Retina Foundation of the Southwest, 9600 N Central Expressway, Ste 200, Dallas, TX 75231 (simoneli @retinafoundation.org). Published Online: January 22, 2015. doi:10.1001/jamaophthalmol.2014.5515. Author Contributions: Drs Li and Birch had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: Stager, Birch. Acquisition, analysis, or interpretation of data: All authors. Drafting of the manuscript: Li. Critical revision of the manuscript for important intellectual content: All authors. Statistical analysis: Li. Obtained funding: Birch. Administrative, technical, or material support: Jost, Morale, De La Cruz, Dao. Study supervision: Stager, Birch. Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported. Funding/Support: This work was supported by grant EY022313 from the National Eye Institute, a 2013 postdoctoral award from Fight for Sight, and the Crystal Charity Ball, Dallas, Texas. Role of the Funder/Sponsor: The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication. 1. Hess RF, Thompson B, Black JM, et al. An iPod treatment of amblyopia: an updated binocular approach. Optometry. 2012;83(2):87-94. 2. Li J, Thompson B, Deng D, Chan LY, Yu M, Hess RF. Dichoptic training enables the adult amblyopic brain to learn. Curr Biol. 2013;23(8):R308-R309. 3. Hess RF, Babu RJ, Clavagnier S, Black J, Bobier W, Thompson B. The iPod binocular home-based treatment for amblyopia in adults: efficacy and compliance. Clin Exp Optom. 2014;97(5):389-398. 4. Li SL, Jost RM, Morale SE, et al. A binocular iPad treatment for amblyopic children. Eye (Lond). 2014;28(10):1246-1253. 5. Moke PS, Turpin AH, Beck RW, et al. Computerized method of visual acuity testing: adaptation of the Amblyopia Treatment Study visual acuity testing protocol. Am J Ophthalmol. 2001;132(6):903-909. 6. Beck RW, Moke PS, Turpin AH, et al. A computerized method of visual acuity testing: adaptation of the early treatment of diabetic retinopathy study testing protocol. Am J Ophthalmol. 2003;135(2):194-205.
In Vivo Biomechanical Mapping of Normal and Keratoconus Corneas Corneal mechanical strength is critical to withstanding intraocular pressure and maintaining normal shape.1,2 In keratoconus, the mechanical stability is compromised,3 which may lead to progressive morphological changes. Therefore, a noninvasive technique capable of accurately measuring the mechanical properties of the cornea may help us understand the mechanism of keratoconus development and improve detection and intervention in keratoconus. We previously developed Brillouin microscopy based on light scattering from inherent acoustic waves in tissues 4 and showed that this technique can provide quantitative estimates of local longitudinal modulus,5 which correlate to the Young and/or shear moduli of the cornea.2,6 Using a clinically viable instrument, for the first time, to our knowledge, we mapped the elastic modulus of normal and keratoconic corneas in vivo. We found distinctive biomechanical features that differentiate normal and keratoconic corneas and therefore have the potential to serve as diagnostic metrics for keratoconus. 480
Methods | The study recruited 6 volunteers with normal corneas (mean [SD] age, 37 [15] years) and 5 patients with advanced keratoconus (mean [SD] age, 43 [7] years). All participants signed an informed consent form and the study was approved by the Partners Human Research Committee (Partners Healthcare Institutional Review Board), in accordance with the principles of the Declaration of Helsinki. We constructed a laser-scanning confocal Brillouin microscope (wavelength, 780 nm; power, 1.5 mW; lateral/axial resolution, 5 μm/30 μm; sensitivity, approximately 10 MHz). The instrument was equipped with wide field-of-view imaging to allow real-time pupil detection and beam positioning (lateral accuracy of
Plano, Texas (Dao, Stager); Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas (Birch). Corresponding Author: Simone L. Li, PhD, Retina Foundation of the Southwest, 9600 N Central Expressway, Ste 200, Dallas, TX 75231 (simoneli @retinafoundation.org). Published Online: January 22, 2015. doi:10.1001/jamaophthalmol.2014.5515. Author Contributions: Drs Li and Birch had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: Stager, Birch. Acquisition, analysis, or interpretation of data: All authors. Drafting of the manuscript: Li. Critical revision of the manuscript for important intellectual content: All authors. Statistical analysis: Li. Obtained funding: Birch. Administrative, technical, or material support: Jost, Morale, De La Cruz, Dao. Study supervision: Stager, Birch. Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported. Funding/Support: This work was supported by grant EY022313 from the National Eye Institute, a 2013 postdoctoral award from Fight for Sight, and the Crystal Charity Ball, Dallas, Texas. Role of the Funder/Sponsor: The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication. 1. Hess RF, Thompson B, Black JM, et al. An iPod treatment of amblyopia: an updated binocular approach. Optometry. 2012;83(2):87-94. 2. Li J, Thompson B, Deng D, Chan LY, Yu M, Hess RF. Dichoptic training enables the adult amblyopic brain to learn. Curr Biol. 2013;23(8):R308-R309. 3. Hess RF, Babu RJ, Clavagnier S, Black J, Bobier W, Thompson B. The iPod binocular home-based treatment for amblyopia in adults: efficacy and compliance. Clin Exp Optom. 2014;97(5):389-398. 4. Li SL, Jost RM, Morale SE, et al. A binocular iPad treatment for amblyopic children. Eye (Lond). 2014;28(10):1246-1253. 5. Moke PS, Turpin AH, Beck RW, et al. Computerized method of visual acuity testing: adaptation of the Amblyopia Treatment Study visual acuity testing protocol. Am J Ophthalmol. 2001;132(6):903-909. 6. Beck RW, Moke PS, Turpin AH, et al. A computerized method of visual acuity testing: adaptation of the early treatment of diabetic retinopathy study testing protocol. Am J Ophthalmol. 2003;135(2):194-205.
In Vivo Biomechanical Mapping of Normal and Keratoconus Corneas Corneal mechanical strength is critical to withstanding intraocular pressure and maintaining normal shape.1,2 In keratoconus, the mechanical stability is compromised,3 which may lead to progressive morphological changes. Therefore, a noninvasive technique capable of accurately measuring the mechanical properties of the cornea may help us understand the mechanism of keratoconus development and improve detection and intervention in keratoconus. We previously developed Brillouin microscopy based on light scattering from inherent acoustic waves in tissues 4 and showed that this technique can provide quantitative estimates of local longitudinal modulus,5 which correlate to the Young and/or shear moduli of the cornea.2,6 Using a clinically viable instrument, for the first time, to our knowledge, we mapped the elastic modulus of normal and keratoconic corneas in vivo. We found distinctive biomechanical features that differentiate normal and keratoconic corneas and therefore have the potential to serve as diagnostic metrics for keratoconus. 480
Methods | The study recruited 6 volunteers with normal corneas (mean [SD] age, 37 [15] years) and 5 patients with advanced keratoconus (mean [SD] age, 43 [7] years). All participants signed an informed consent form and the study was approved by the Partners Human Research Committee (Partners Healthcare Institutional Review Board), in accordance with the principles of the Declaration of Helsinki. We constructed a laser-scanning confocal Brillouin microscope (wavelength, 780 nm; power, 1.5 mW; lateral/axial resolution, 5 μm/30 μm; sensitivity, approximately 10 MHz). The instrument was equipped with wide field-of-view imaging to allow real-time pupil detection and beam positioning (lateral accuracy of
